JP5779980B2 - Sheet processing apparatus and sheet processing method - Google Patents

Description

  The present invention relates to an image forming system constructed by combining a color printer, a monochrome printer, a copying machine, a multi-function printer, a finisher, and the like, with the leading ends of a plurality of recording sheets after image formation overlapped and sent. The present invention relates to a sheet processing apparatus and a sheet processing method that are suitable for application to a sheet stacking and feeding apparatus.

  In recent years, an image forming system in which an image forming apparatus that forms an image based on image information and a post-processing apparatus that performs post-processing on a recording sheet after image formation has been often constructed. The post-processing apparatus includes a sheet processing apparatus that superimposes and feeds a plurality of sheet materials, a punch processing apparatus that opens punch holes in a bundle of sheets on which a plurality of sheet materials are superimposed, and a sheet on which a plurality of sheet materials are superimposed. Staple processing devices that apply staples to a bundle are used. A model in which these device functions are mounted in one post-processing device is also manufactured.

  With regard to this type of sheet processing apparatus, Patent Document 1 discloses a sheet stacking apparatus. According to this sheet stacking apparatus, the stacking unit, the discharging unit, and the stacking unit are provided, and it is determined whether or not to stack the sheets according to the sheet information such as the paper type. A plurality of sheets are superposed by means. Thereafter, the plurality of superimposed sheets are stacked on the stacking means by the discharging means and discharged. By configuring the sheet stacking device in this way, it is possible to increase the processing time of the preceding sheet, as well as sheet rounding, buckling, and extrusion of already loaded sheets due to the difference in paper type. Etc. can be prevented.

Japanese Patent Laying-Open No. 2010-06559 (FIG. 1 on page 4)

  By the way, according to the sheet stacking apparatus as seen in Patent Document 1, there are the following problems.

  i. According to the sheet stacking apparatus of Patent Document 1, while the sheet processing of the preceding sheet bundle is being performed on the stacking unit, the first several sheets of subsequent sheets conveyed from the image forming apparatus are overlapped. ing. Then, after the sheet processing of the preceding sheet bundle is completed and the preceding sheet bundle is discharged from the stacking unit, the overlapped standby sheet is conveyed onto the stacking unit, and thereafter the number of sheets constituting the subsequent sheet bundle The process of carrying one sheet at a time onto the stacking means is executed until the value reaches.

  In Patent Document 1, sheet superposition is controlled according to the type of paper, but the load on the transport drive system changes according to the number of sheets to be superposed, so that the leading edge of the sheet shifts without overlapping. There's a problem.

  ii. Here, consider a case where a sheet processing apparatus 200 using a switchback mechanism as shown in FIG. 12 is configured. The sheet processing apparatus 200 includes a take-in roller 11, a sheet detection sensor 12, a switchback transport unit 20, a branch unit 30, and a standby position transport unit 40.

  In the sheet processing apparatus 200, for example, when four sheets of paper P1 to P4 are overlapped and four sheets of sheets P1, P2, P3, and P4 (sheet bundle) are output, first, the sheet detection sensor 12 is the first sheet. Is detected. The take-in roller 11 takes in the paper P <b> 1 detected by the paper detection sensor 12 into the switchback conveyance unit 20. The switchback conveying unit 20 conveys the paper P1 taken in by the take-in roller 11 toward a predetermined overlapping position, and then reversely conveys the paper P1 from the overlapping position to a predetermined standby position.

  Next, when the paper detection sensor 12 detects that the second sheet P <b> 2 is captured, the capture roller 11 captures the paper P <b> 2 detected by the paper detection sensor 12 into the switchback transport unit 20. The switchback transport unit 20 transports the paper P2 captured by the capture roller 11 toward the overlapping position. On the other hand, based on the capture of the second sheet P2 whose capture is detected by the sheet detection sensor 12, the standby position transport unit 40 transports the first sheet P1 at the standby position toward the overlapping position. . Thereby, after the paper P1 and the paper P2 are overlapped at the overlapping position, the sheet bundle (P1 + P2) is reversely conveyed from the overlapping position to the standby position.

  Further, when the paper detection sensor 12 detects the capture of the third sheet P3, the capture roller 11 captures the paper P3 detected by the paper detection sensor 12 into the switchback transport unit 20. The switchback transport unit 20 transports the paper P3 captured by the capture roller 11 toward the overlapping position. On the other hand, the standby position transport unit 40 superimposes the first and second sheets P1 and P2 at the standby position based on the capture of the third sheet P3 whose capture is detected by the sheet detection sensor 12. Transport toward the position. Thus, after the sheets P1, P2 and the sheet P3 are overlapped at the overlapping position, the sheet bundle (P1 + P2 + P3) is reversely conveyed from the overlapping position to the standby position.

  Further, when the paper detection sensor 12 detects that the fourth sheet P4 has been taken in, the take-in roller 11 takes in the paper P4 detected by the paper detection sensor 12 into the switchback transport unit 20. The switchback transport unit 20 transports the paper P4 captured by the capture roller 11 toward the overlapping position.

  On the other hand, based on the capture of the fourth sheet P4 whose capture is detected by the sheet detection sensor 12, the standby position transport unit 40 causes the first, second, and third sheets P1, P1 of the standby position to be captured. P2 and P3 are conveyed toward the overlapping position. Accordingly, after the sheets P1, P2, P3 and the sheet P4 are overlapped at the overlapping position, the sheet bundle (P1 + P2 + P3 + P4) is discharged without waiting at the standby position.

  However, according to the sheet processing apparatus 200, the load on the driving system of the standby position transport unit 40 and the like changes as the number of sheets re-transported from the standby position transport unit 40 increases. For this reason, if the same time is set every time after the paper detection sensor 12 is turned on and control is performed to start transporting the standby side P1, P2, P3, as shown in the broken circle in the figure, the paper P1 , P2 and P3 are each overlapped, a conveyance delay occurs, and there is a problem that four sheets of sheets P1, P2, P3, and P4 with their leading ends slightly shifted are discharged.

  Accordingly, the present invention solves the above-described problems, and devise a sheet material superposition method so that the front end portions of a plurality of sheet materials can be polymerized with good reproducibility, and a sheet processing method. The purpose is to provide.

In order to solve the above-described problem, the sheet processing apparatus according to claim 1 outputs a bundled sheet member by superimposing a leading end portion of the second and subsequent sheet materials on a leading end portion of the first sheet material. A sheet processing apparatus that detects the loading of the sheet material, and the sheet material detected by the sheet detection unit, conveys the sheet material toward a predetermined overlapping position, and then the stacking A first sheet conveying unit that reversely conveys from the alignment position to a predetermined standby position, and the sheet material that is reversely conveyed to the standby position by the first sheet conveying unit is directed from the standby position to the overlapping position. a second sheet conveying portion for conveying Te, the conveyance time ranging from incorporation detection position of the sheet material of the second and subsequent sheets detected by the sheet detecting portion at a position superposed is the paper And each time, as compared with the conveyance start timing when the sheet material is less likely to stand in the standby position, as the sheet material to wait in the waiting position is increased, the second to advance the conveyance start timing of the sheet material And a control unit that controls the sheet conveying unit.

  According to the sheet processing apparatus of claim 1, the sheet detection is performed when the leading end portion of the second and subsequent sheets is overlapped on the leading end portion of the first sheet material and the bundled sheet member is output. A first sheet conveying unit and a control unit. The sheet detection unit detects the intake of the sheet material. The first sheet conveying unit takes in the sheet material detected by the sheet detecting unit and conveys the sheet material toward a predetermined overlapping position, and then reversely conveys the sheet material from the overlapping position to a predetermined standby position. The second sheet conveying unit conveys the sheet material reversely conveyed to the standby position by the first sheet conveying unit from the standby position toward the overlapping position. Based on these assumptions, the control unit changes the conveyance start timing of the sheet material conveyed from the standby position toward the overlapping position according to the number of standby sheets of the plurality of sheet materials standby at the standby position. The second sheet conveying unit is controlled. With this control, the alignment accuracy does not decrease due to the difference in the number of sheets to be stacked, and even if the number of stacked sheets changes, the sheets can be stacked at the same position.

The sheet processing apparatus according to claim 2 , further comprising a counting unit that counts the number of sheets that are waiting at the standby position, wherein the control unit waits at the standby position counted by the counting unit. The conveyance start timing of the sheet material waiting at the standby position is controlled based on the number of sheets .

The sheet processing apparatus according to claim 3, before Symbol control unit, said a leading edge detecting time and trailing edge detection time of the sheet material is detected by the sheet detection unit, based on the length of the sheet material 2 The sheet material taking-in speed after the first sheet is calculated, and the conveying speed of the sheet material conveyed from the standby position to the overlapping position is adjusted based on the calculated sheet material taking-in speed. Is.

The sheet processing method according to claim 4 is a sheet processing method for superimposing the leading end portions of the second and subsequent sheet materials on the leading end portion of the first sheet material, and outputting a bundled sheet member, Sequentially detects the sheet material to be taken into the overlapping position, takes in the detected sheet material, conveys it toward a predetermined overlapping position, and then reversely conveys from the overlapping position to a predetermined standby position. Holding the sheet material, transporting the second and subsequent sheet materials detected to be taken toward the overlapping position, and one sheet based on the detection time of the second and subsequent sheet materials. When the sheet material after the first sheet is transported from the standby position toward the overlapping position and the plurality of sheet materials to be sequentially captured are overlapped at the overlapping position, the second and subsequent sheet materials are transferred. The sheet material that waits at the standby position as compared to the conveyance start timing when the sheet material that waits at the standby position is limited by the conveyance time from the sheet material capture detection position to the overlap position. As the number increases, the conveyance start timing of the sheet material is advanced .

According to the sheet processing apparatus according to claim 1 and the sheet processing method according to claim 4 , two sheets are conveyed in such a manner that a plurality of sheet materials to be sequentially taken are overlapped with each other at the overlapping position. The control part which controls a part is provided.

  With this configuration, the alignment accuracy does not decrease due to the difference in the number of sheet materials to be stacked, and even if the number of stacked sheets changes, the sheet materials can be stacked at the same position with good reproducibility.

According to the sheet processing apparatus according to claim 2, adjusts the conveyance start timing of the sheet material of the first sheet after being transported to a position superimposed from the standby position based on the incorporation detection time of the second and subsequent sheets of the sheet material Therefore, the alignment accuracy does not decrease due to the difference in the number of sheet materials to be stacked, and even if the number of stacked sheets changes, they can be stacked at the same position.

According to the sheet processing apparatus of the third aspect , the conveyance start timing of the first and subsequent sheet materials conveyed from the standby position to the overlapping position is adjusted based on the take-in speed of the second and subsequent sheet materials. Therefore, the alignment accuracy does not deteriorate due to the difference in the taking-in speed of the sheet materials to be stacked, and even if the number of stacked sheets changes, they can be stacked at the same position.

1 is a block diagram illustrating a configuration example of a sheet overlap delivery device 100 as an embodiment according to the present invention. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 1) of the sheet | seat overlap sending device 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 2) of the sheet | seat overlap sending apparatus 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 3) of the paper overlap sending apparatus 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 4) of the paper overlap sending apparatus 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 5) of the paper overlap sending apparatus 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 6) of the paper overlap sending apparatus 100. FIG. (A) And (B) is explanatory drawing which shows the operation example (the 7) of the sheet | seat overlap sending apparatus 100. FIG. It is a graph which shows the example of conveyance start timings, such as the forward / reverse rotation roller. (A)-(F) are operation | movement time charts which show the example of a drive start timing of the conveyance motor 44. FIG. 6 is a flowchart illustrating an example of control of the sheet stacking apparatus 100. It is explanatory drawing which shows the structural example and operation example of the sheet processing apparatus 200 concerning a prior art example.

  Hereinafter, a sheet processing apparatus and a sheet processing method according to embodiments of the present invention will be described with reference to the drawings. 1 forms an example of a sheet processing apparatus, and stacks the leading end portions of the second and subsequent sheets on the leading end portion of the first sheet material to form a sheet material in a bundle state (hereinafter referred to as a bundled sheet material). The paper Pi). The sheet stacking apparatus 100 includes a take-in roller 11, a sheet detection sensor 12, a switchback transport unit 20, a branch unit 30, a standby position transport unit 40, and a control unit 50. The sheet material includes plain paper, thick paper, coated paper, thin paper, film, and the like, and also includes paper Pi having different paper types and basis weights. A bundle of sheets Pi is also referred to as a sheet bundle.

  The take-in roller 11 is provided on the upstream side of the sheet overlap delivery device 100. Here, the upstream side is a paper feeding side for taking in a sheet material, for example, a side on which paper Pi (i = 1 to n) recorded from the image forming apparatus is discharged. The downstream side is the paper discharge side for sending out the paper Pi, and is, for example, the side of the post-processing device where the paper bundle is post-processed. The drive source of the take-in roller 11 may be provided separately from the switchback transport unit 20, but may also serve as the transport motor 23 of the switchback transport unit 20.

  The sheet detection sensor 12 constitutes an example of a sheet detection unit and is disposed on the upstream side of the take-in roller 11. The paper detection sensor 12 detects the capture of the paper Pi and generates a paper detection signal S12. The sheet detection signal S12 rises (turns on) from a low level to a high level when, for example, the leading end of the sheet Pi is detected. The paper detection sensor 12 is a transmissive or reflective optical sensor.

  The switchback conveyance unit 20 constitutes an example of a first sheet conveyance unit, and is disposed on the downstream side of the take-in roller 11. The switchback transport unit 20 takes in the paper Pi detected by the paper detection sensor 12, transports the paper Pi toward a predetermined overlapping position, and then reversely transports the paper Pi from the overlapping position to a predetermined standby position. The paper Pi has a function of through-passing downstream as it is without being reversely conveyed. The switchback conveyance unit 20 includes a switchback conveyance path 21, a forward / reverse rotation roller 22, and a conveyance motor 23.

  The forward / reverse roller 22 is provided in the vicinity of the discharge port of the switchback transport path 21. The forward / reverse roller 22 has a drive roller and a driven roller, and the drive roller rotates clockwise when the paper Pi is taken into the switchback conveyance path 21 and when the paper is sent out (forward rotation: see arrows in the figure). Is done. When the paper Pi is fed into the standby conveyance path, it is rotated (reversely rotated) counterclockwise.

  The transport motor 23 is attached to a predetermined position of the switchback transport unit 20, is connected to the forward / reverse roller 22, and rotates the forward / reverse roller 22 in a predetermined direction. Of course, the take-in roller 11 may be rotationally driven by using the transport motor 23 as well. One conveyance motor 23 can be omitted.

  The branching unit 30 is provided between the switchback conveying unit 20 and the standby position conveying unit 40 and branches a take-in conveying path 31 for taking in the paper Pi and a standby conveying path 32 for waiting the paper Pi. For example, the branch part 30 includes a long and narrow triangular prism-shaped branch member 33. The conveyance path 31 and the conveyance path 32 are separated from each other by a triangular prism-shaped acute angle portion of the branch member 33.

  Of course, a solenoid element (not shown) may be attached to the branch member 33 to perform branch control of the paper Pi. For example, when taking in the paper Pi, the paper Pi is guided to the forward / reverse roller 22 so as to descend the acute angle portion of the branch member 33. When waiting for the paper Pi, the acute angle portion of the branching member 33 may be raised to guide the paper Pi to the standby position transport unit 40.

  Note that the overlapping position of the paper Pi may be anywhere as long as it is within the range from the triangular prism-shaped acute angle portion of the branch member 33 to the nip position of the forward / reverse roller 22 of the switchback transport unit 20. It suffices if the leading end of the first sheet P1 and the leading ends of the second and subsequent sheets P2, P3, P4,...

  In this example, a standby position transport unit 40 is provided on the right side of the branch unit 30. The standby position transport unit 40 is configured to detect the capture of the second and subsequent sheets Pi detected by the sheet detection sensor 12 for the sheet Pi reversely transported to the standby position by the switchback transport unit 20. Subsequent sheets Pi are conveyed from the standby position toward the overlapping position. The standby position transport unit 40 includes a standby transport path 41, two forward / reverse rollers 42 and 43, and a transport motor 44.

  The forward / reverse roller 42 has a drive roller and a driven roller, and is disposed near the paper entrance / exit of the standby conveyance path 41. The forward / reverse roller 43 also has a drive roller and a driven roller, and is disposed at the end position of the standby conveyance path 41. Established. The forward and reverse rollers 42 and 43 are rotated in the counterclockwise direction when the sheet Pi is taken into the standby conveyance path 41 from the switchback conveyance path 21 (reverse rotation: see arrows in the figure). When the paper Pi is sent out from the standby conveyance path 41 to the switchback conveyance path 21, the drive rollers of the forward and reverse rotation rollers 42 and 43 are rotated in the clockwise direction (forward rotation).

  The transport motor 44 is attached to a predetermined position of the standby position transport unit 40, connected to the two forward / reverse rollers 42 and 43, and rotationally drives the forward / reverse rollers 42 and 43 in a predetermined direction. For example, a brushless motor (induction motor) is used as the above-described transport motors 23 and 44.

  The control unit 50 sequentially switches the plurality of sheets Pi taken into the switchback transport unit 20 via the take-in roller 11 at the stacking position so that the leading ends of the respective sheets Pi overlap each other. The position transport unit 40 is controlled. For example, the control unit 50 operates based on a reference clock signal (hereinafter referred to as a CLK signal), an A / D conversion unit 51, a counter 52, a ROM (Read Only Memory) 53, a RAM (Random Access Memory) 54, a central calculation. An apparatus (Central Processing Unit: hereinafter referred to as CPU 55) and a motor control unit 56 are configured.

  An operation & display unit 48 is connected to the control unit 50. The control unit 50 reads out the system program Dp stored in the ROM 53 and various processing programs by the operation of the operation & display unit 48 and develops them in the RAM 54, and the operation of the sheet overlap feeding device according to the developed system program Dp. Centralized control. For example, the CPU 55 executes sheet overlap sending control in the switchback conveyance unit 20 and the standby position conveyance unit 40 according to the developed program.

  The operation & display unit 48 includes a touch panel and an LCD (Liquid Crystal Display), and is operated, for example, so as to set various number-overlap modes. In this example, a one-sheet stacking mode, a two-sheet stacking mode, a three-sheet stacking mode, and a four-sheet stacking mode can be set. Here, the one-sheet superposition mode is a state in which the first sheet P1 is taken into the standby position transport unit 40, and another sheet P2 is taken into the one sheet P1 from the outside. An operation of discharging a total of two bundles of paper P1, P2 with the leading ends overlapped.

  The two-sheet superposition mode is a state in which the first sheet P1 is taken into the standby position transport unit 40, and two sheets P2, P3 are further taken into the one sheet P1 from the outside. An operation of discharging a total of three bundles of paper P1, P2, and P3 with the leading ends overlapped.

  The three-sheet superposition mode is a state in which the first sheet P1 is taken into the standby position transport unit 40, and three sheets P2, P3, and P4 are further taken into the one sheet P1 from the outside. This refers to an operation of discharging a total of four sheets of paper P1, P2, P3, P4 with the respective leading ends overlapped.

  The four-sheet superposition mode is a state in which the first sheet P1 is taken into the standby position transport unit 40, and four sheets P2, P3, P4, and P5 are further taken into the one sheet P1 from the outside. The operation of discharging the total of five sheets of sheets P1, P2, P3, P4, and P5 with the respective leading ends overlapped.

  The operation & display unit 48 includes various operation buttons such as a numeric button and a start button, and outputs operation data D48 by button operation including setting of various number overlap mode to the control unit 50. When the paper overlap sending device 100 is used in tandem with an image forming apparatus (not shown) on the upstream side, the operation data D48 may be supplied from the image forming apparatus, and therefore the operation & display unit 48 may be omitted.

  The input side of the A / D converter 51 is connected to the paper detection sensor 12, and the output side thereof is connected to the counter 52 and the system bus 57. The A / D converter 51 receives the paper detection signal S12 from the paper detection sensor 12, converts the paper detection signal S12 from analog to digital, and outputs the paper detection data D12 to the counter 52 and the CPU 55.

  The counter 52 constitutes an example of a counting unit, and counts the number of sheets Pi waiting at the standby position. For example, the counter 52 counts the number of sheets Pi based on the sheet detection data D12 output from the A / D converter 51 and outputs the sheet number data D52. The sheet number data D52 is output from the counter 52 to the CPU 55. The CPU 55 can recognize the number of sheets Pi during standby based on the sheet number data D52 output from the counter 52, and adjusts the driving start timing of the transport motor 44 based on the number of sheets Pi. This adjustment makes it possible to superimpose the leading edge of the subsequent paper Pi and the standby paper Pi with good reproducibility.

  The motor control unit 56 is connected to the transport motors 23 and 44. The motor control unit 56 controls the transport motors 23 and 44 based on the motor drive data D56. For example, the motor control unit 56 decodes the motor drive data D56 and generates motor control signals S23 and S44. The motor drive data D56 is data for superimposing the subsequent paper Pi and the leading edge of the standby paper Pi with good reproducibility, and is output from the CPU 55 to the motor control unit 56. The motor control signal S23 is output from the motor control unit 56 to the transport motor 23.

  The motor control signal S44 is a signal for superimposing the succeeding paper Pi and the leading edge of the standby paper Pi with good reproducibility, and is output from the motor control unit 56 to the transport motor 44. In this example, the motor control signal S44 (1) is output in the one-ply mode and the motor control signal S44 (2) is output in the two-ply mode according to the setting of the superposition operation mode. In the mode, the motor control signal S44 (3) is output. In the four-stack mode, the motor control signal S44 (4) is output.

  The CPU 55 sequentially controls the standby position transport unit 40 so as to sequentially change the transport start timing when a plurality of sheets Pi are stacked in accordance with the standby number of the plurality of sheets Pi waiting at a predetermined position. . In this example, the paper Pi is waited by the standby position transport unit 40, and the standby number of the paper Pi is counted by the counter 52. The CPU 55 changes (adjusts) the transport start timing of the first and subsequent sheets of paper Pi that are transported from the standby position to the overlapping position by the standby position transport section 40 based on the detection detection time of the second and subsequent sheets of paper Pi. To do.

  For example, the CPU 55 sets the waiting number of sheets Pi to be waiting at the standby position counted by the counter 52 by limiting the conveyance time from the detection detection position of the second and subsequent sheets Pi to the overlapping position. The standby position conveyance unit 40 is controlled so that the conveyance start timing of the paper Pi is advanced as the number of sheets Pi waiting at the standby position increases as compared to the conveyance start timing when the number is small.

  Next, with reference to FIG. 2 to FIG. 8, an operation example (Nos. 1 to 7) of the sheet overlap delivery device 100 will be described. In this example, a case where the sheet Pi (i = 1 to 5) is overlapped and sent by setting the one-sheet overlap mode, the two-sheet overlap mode, the three-sheet overlap mode, and the four-sheet overlap mode will be described.

  2A, the take-in roller 11 and the forward / reverse roller 22 are driven, and the first sheet P1 is drawn into the switchback transport unit 20. At this time, the paper detection sensor 12 detects the paper P1. 2B, the first sheet P1 arrives at the switchback transport unit 20. When arriving, the rear end of the sheet P1 is positioned downstream of the triangular prism-shaped acute angle portion of the branching member 33.

  3A, the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 are driven, the first sheet P1 is conveyed in reverse, and reaches the standby position conveyance unit 40. The paper Pi that has reached the standby position transport unit 40 is a standby sheet. At the same time, the paper detection sensor 12 detects the second paper P2.

  3B, the take-in roller 11 and the forward / reverse roller 22 are driven, and the second sheet P2 (following sheet) is drawn into the switchback conveyance unit 20 and 2 After X seconds from the time when the first sheet P2 is detected, the forward / reverse rollers 42 and 43 are driven to start conveying the first sheet P1 (standby sheet) to the switchback conveying unit 20. Then, the leading ends of the first and second sheets P1, P2 arrive at the switchback transport unit 20, and the leading ends of the sheets P1, P2 overlap each other.

  4A, the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 are driven in a state where the leading ends of the sheets P1 and P2 are overlapped, and when the overlap is completed, the sheets P1 and The rear end portion of P2 is positioned downstream of the triangular prism-shaped acute angle portion of the branching member 33. As a result, a bundle of two sheets P1 and P2 can be discharged (single sheet stacking mode).

  According to the sheet stacking and feeding apparatus 100 shown in FIG. 4B, the two-sheet stack in which the leading ends of the sheets P1 and P2 overlap each other is reversely conveyed by the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 to be switched. It reaches the standby position transport unit 40 from the back transport unit 20. At the same time, the sheet detection sensor 12 detects the third sheet P3.

  5A, the take-in roller 11 and the forward / reverse roller 22 are driven, and the third sheet P3 is drawn into the switchback transport unit 20, and the transport start timing starts from X seconds. After changing to Y seconds and Y seconds after the time when the third sheet P3 is detected, the forward and reverse rollers 42 and 43 start transporting the two sheets of sheets P1 and P2 to the switchback transport unit 20. Then, the leading ends of the first to third sheets P1, P2, and P3 arrive at the switchback transport unit 20, and the leading ends of the sheets P1, P2, and P3 overlap each other.

  5B, the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 are driven in a state where the leading ends of the sheets P1, P2, and P3 are overlapped, and when the overlap is completed, The rear end portions of P1, P2, and P3 are positioned downstream of the triangular prism-shaped acute angle portion of the branching member 33. As a result, a bundle of three sheets P1, P2, and P3 can be discharged (two-sheet stacking mode).

  6A, the sheet stack of three sheets in which the leading ends of the sheets P1, P2, and P3 overlap is reversely conveyed by the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43. Then, the switchback transport unit 20 reaches the standby position transport unit 40. At the same time, the paper detection sensor 12 detects the fourth paper P4.

  6B, the take-in roller 11 and the forward / reverse rotation roller 22 are driven, and the fourth sheet P4 is drawn into the switchback transport unit 20, and the transport start timing starts from Y seconds. The time is changed to Z seconds, and Z seconds after the time when the fourth sheet P4 is detected, the forward and reverse rollers 42 and 43 start transporting the three sheets of sheets P1, P2, and P3 to the switchback transport unit 20. To do. Then, the leading ends of the first to fourth sheets P1, P2, P3, and P4 arrive at the switchback transport unit 20, and the leading ends of the sheets P1, P2, P3, and P4 overlap each other.

  7A, the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 are driven in a state where the leading ends of the sheets P1, P2, P3, and P4 are overlapped, and when the overlap is completed. The rear end portions of the sheets P1, P2, P3, and P4 are positioned downstream of the triangular column-shaped acute angle portion of the branch member 33. As a result, a bundle of four sheets P1, P2, P3, and P4 can be discharged (three-sheet stacking mode).

  7B, the sheet stack of four sheets in which the leading ends of the sheets P1, P2, P3, and P4 overlap each other is reversed by the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43. It is transported and reaches the standby position transport unit 40 from the switchback transport unit 20. At the same time, the paper detection sensor 12 detects the fifth paper P5.

  8A, the take-in roller 11 and the forward / reverse rotation roller 22 are driven, the fifth sheet P5 is drawn into the switchback transport unit 20, and the transport start timing is from Z seconds. The time is changed to 0 seconds, and at the time when the fifth sheet P5 is detected, the forward and reverse rollers 42 and 43 start transporting the four sheets of sheets P1, P2, P3, and P4 to the switchback transport unit 20. . Then, the leading ends of the first to fifth sheets P1, P2, P3, P4, P5 arrive at the switchback transport unit 20, and the leading ends of the sheets P1, P2, P3, P4, P5. Overlap.

  8B, the forward / reverse rotation roller 22 and the forward / reverse rotation rollers 42 and 43 are driven in a state in which the leading ends of the sheets P1, P2, P3, P4, and P5 are overlapped, and the overlap is performed. When completed, the rear ends of the sheets P1, P2, P3, P4, and P5 are positioned on the downstream side of the triangular prism-shaped acute angle portion of the branch member 33. As a result, a bundle of five sheets P1, P2, P3, P4, and P5 can be discharged (four-sheet stacking mode).

  Here, an example of the conveyance start timing of the forward / reverse rotation roller 42 and the like in the sheet overlap delivery device 100 shown in FIG. 1 will be described. The graph shown in FIG. 9 summarizes the sheet detection time by the sheet detection sensor 12 and the conveyance start timing of the forward / reverse roller 42 and the like in each overlap operation mode. The forward / reverse roller 43 may be controlled similarly to the forward / reverse roller 42.

  In this example, the operation timing of the transport motor 44 differs depending on the number of sheets Pi stacked after the sheet detection sensor 12 is turned on. In FIG. 9, the vertical axis represents the paper Pi taking-in speed V, which is a speed depending on the taking-in roller 11 and the forward / reverse roller 42. The take-in roller 11 depends on the transport motor 23, and the forward / reverse roller 42 depends on the transport motor 44.

  The thick solid line in the figure is the paper Pi take-in speed V, which is the target speed Vm at the time of superposition. The horizontal axis represents an elapsed time t after the forward / reverse rotation roller 42 is turned on (started up). t0 is the time when the paper detection sensor 12 detects the paper Pi, and t1 is the time when the paper Pi is superimposed. It has been found that the elapsed time from the forward / reverse rotation roller 42 carrying the paper Pi to the target speed Vm varies depending on the number of stacked sheets.

  The thin solid line in the figure is the rising conveyance speed characteristic of the forward / reverse roller 42 in the one-sheet superposition mode. The forward / reverse roller 42 is X seconds after time t0 when the paper detection sensor 12 detects the second paper P2. Is a conveyance speed characteristic line from when is started up to the target speed Vm. X seconds after the time t0 when the second sheet P2 is detected is the conveyance start timing (time tx) in the one-sheet overlapping mode. At time tx, X seconds are counted with reference to the CLK signal at time t0.

  The broken line in the figure is the rising conveyance speed characteristic of the forward / reverse roller 42 in the two-sheet superposition mode. The forward / reverse roller 42 is moved Y seconds after the time t0 when the paper detection sensor 12 detects the third paper P3. It is a conveyance speed characteristic line from starting up to the target speed Vm. Y seconds after the time t0 when the third sheet P3 is detected is the conveyance start timing (time ty) in the two-sheet overlap mode. At time ty, Y seconds are counted with reference to the CLK signal at time t0.

  The one-dot chain line in the figure is the rising conveyance speed characteristic of the forward / reverse roller 42 in the three-sheet superposition mode, and the forward / reverse roller 42 is Z seconds after time t0 when the paper detection sensor 12 detects the fourth paper P4. Is a conveyance speed characteristic line from when is started up to the target speed Vm. Z seconds after the time t0 when the fourth sheet P4 is detected is the conveyance start timing (time tz) in the three-sheet stacking mode. At time tz, Z seconds are counted with reference to the CLK signal at time t0.

  The two-dot chain line in the figure is the rising conveyance speed characteristic of the forward / reverse rotation roller 42 in the four-sheet superposition mode. At the same time t0 when the paper detection sensor 12 detects the fifth sheet P5, the forward / reverse rotation roller 42 It is a conveyance speed characteristic line from starting up to the target speed Vm. The same time as the time t0 when the fifth sheet P5 is detected is the conveyance start timing (time t0) in the four-sheet overlapping mode.

  As a result, the counter 52 counts the transfer time (t1-t0) from the detection detection position of the second and subsequent sheets P2, P3,. Compared to the conveyance start timing when the number of sheets P2 waiting at the standby position is small, the conveyance start timing of the sheets P2, P3, P4 increases as the number of sheets P2, P3, P4, etc. waiting at the standby position increases. The standby position transport unit 40 can be controlled so as to speed up (X> Y> Z> 0).

  Next, with reference to FIGS. 10A to 10F, the drive start timing of the conveyance motor 44 in the sheet overlap delivery device 100 will be described. The operation time charts shown in FIGS. 10A to 10F summarize the sheet detection timing by the sheet detection sensor 12 and the drive start timing of the conveyance motor 44 in each overlap operation mode.

  The CLK signal shown in FIG. 10A is a reference signal for driving the control unit 50 shown in FIG. The paper detection signal S12 illustrated in FIG. 10B is output from the paper detection sensor 12 illustrated in FIG. 1 to the A / D conversion unit 51. The sheet detection signal S12 rises from a low level to a high level to indicate the presence of a sheet (sheet arrival). The paper detection signal S12 falls from the high level to the low level to indicate no paper (paper not reached). In this example, the conveyance start timing is set based on the CLK signal at time t0.

  The motor control signal S44 (1) shown in FIG. 10C is set in the single-stack mode, and is a signal that rises from a low level to a high level, for example, X seconds after the rising time t0 of the paper detection signal S12. The motor control signal S44 (2) shown in FIG. 10D is set in the two-sheet superposition mode, and is, for example, a signal that rises from a low level to a high level Y seconds after the rising time t0 of the paper detection signal S12.

  The motor control signal S44 (3) shown in FIG. 10E is set in the three-sheet superposition mode, and is, for example, a signal that rises from a low level to a high level after Z seconds from the rising time t0 of the paper detection signal S12. The motor control signal S44 (3) shown in FIG. 10F is set in the four-sheet superposition mode, and is, for example, a signal that rises from a low level to a high level simultaneously with the rising time t0 of the sheet detection signal S12.

  These motor control signals S44 (1) to (4) are managed by the CLK signal shown in FIG. 10A, and are output from the motor control unit 56 shown in FIG. Thereby, in the control unit 50, a plurality of sheets Pi sequentially taken into the switchback transport unit 20 via the take-in roller 11 are sequentially arranged at the overlapping positions based on the sheet detection signal S12 obtained from the sheet detection sensor 12. The switchback conveyance unit 20 and the standby position conveyance unit 40 can be controlled so that the leading ends of the paper Pi are overlapped.

  Next, with reference to FIG. 11, a control example of the sheet stacking and sending apparatus 100 regarding the sheet processing method will be described. In the sheet stacking and feeding apparatus 100, a sheet bundle in which the leading ends of the second and subsequent sheets P2, P3, P4, and P5 are superimposed on the leading end of the first sheet P1, and a maximum of five sheets P1 to P5 are bundled. Is output (paper Pi: i = 1 to n = 5). The paper detection sensor 12 detects the paper Pi taken into the switchback transport unit 20 and generates a paper detection signal S12.

  When the CPU 55 sequentially stacks the plurality of sheets Pi taken into the switchback transport unit 20 at the stacking position, the CPU 55 performs the stacking of a plurality of sheets according to the standby number of the plurality of sheets Pi waiting on the standby position transport unit 40. The standby position transport unit 40 is controlled so as to sequentially change the transport start timing. In this example, it is assumed that after the last sheet Pi is superimposed on the standby-side sheets P1, P2, P3, etc., the standby position transport unit 40 outputs the sheet as it is without waiting. In the following, the case of the 1-sheet stacking mode to the 4-sheet stacking mode will be described separately.

[Single stack mode]
In step ST1 shown in FIG. 11, the CPU 55 inputs the setting of the overlapping operation mode. In this example, the stacking operation mode includes a single stacking mode, a two stacking mode, a three stacking mode, and a four stacking mode, and the user operates the operation & display unit 48 to set the single stacking mode to the CPU 55. To be set to In step ST2, the CPU 55 branches the control depending on whether or not the overlapping operation mode is finished.

  In this example, since the one-sheet overlap mode is set, the sheet detection sensor 12 shown in FIG. 1 detects the first sheet P1. The paper detection sensor 12 outputs a paper detection signal S12 that rises from a low level to a high level indicating arrival of the paper to the A / D converter 51.

  In step ST3, the CPU 55 takes in the first sheet P1 and causes the standby position transport unit 40 to wait. At this time, the switchback conveyance unit 20 takes in the first sheet P1 detected by the sheet detection sensor 12 and conveys it to a predetermined overlapping position, and then, from the overlapping position to a predetermined standby position conveying unit. Inverted to 40. As a result, the first sheet P1 waits at the standby position transport unit 40.

  Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the first sheet P1 is the first sheet or the other number. In this example, since the one-sheet stacking mode is set, the switchback conveyance unit 20 takes in the first sheet P2 in step ST5, and the CPU 55 determines in step ST6 that the sheet detection sensor 12 is turned on. After X seconds, conveyance of the first sheet P1 of the standby position conveyance unit 40 to the switchback conveyance unit 20 is started.

  At this time, when the switchback transport unit 20 takes in the first overlapped sheet P2 detected by the sheet detection sensor 12 and transports it to a predetermined stacking position, from the rising time t0 of the sheet detection signal S12. After X seconds, a motor control signal S44 (1) that rises from the low level to the high level shown in FIG. In the standby position transport unit 40, the first sheet P <b> 1 is transported from the standby position toward the overlapping position based on the rotation of the transport motor 44. As a result, the leading end of the sheet P1 and the leading end of the sheet P2 are overlapped at the overlapping position, and a sheet bundle in which a total of two sheets P1, P2 are overlapped can be sent (see FIG. 4A). Thereafter, in step ST2, the CPU 55 detects the end of the one-sheet stacking mode and ends the sheet stacking control.

[Double stack mode]
Further, when the two-sheet superimposing mode is set in step ST1, the CPU 55 takes in the first sheet P1 in step ST3 in the same manner as in the single-sheet superimposing mode, and places the first sheet P1 in the standby position. The transport unit 40 is put on standby. Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the first sheet P1 is the first sheet or the other number.

  In this example, in the same manner as in the single sheet stacking mode, the switchback conveyance unit 20 takes in the first sheet P2 in step ST5, and in step ST6, the CPU 55 X seconds after the sheet detection sensor 12 is turned on. Later, the first sheet P1 of the standby position transport unit 40 is started to be transported to the switchback transport unit 20. As a result, the leading end of the sheet P1 and the leading end of the sheet P2 are overlapped at the overlapping position, and a sheet bundle in which a total of two sheets P1 and P2 are overlapped can be reversed and conveyed to the standby position conveying unit 40. Become.

  In this state, the switchback conveyance unit 20 reversely conveys a total of two sheets P1 and P2 from the overlapping position to the standby position conveyance unit 40. In step ST2, the CPU 55 detects that the two-sheet stacking mode has not been completed. In step ST3, the standby position transport unit 40 waits for a sheet bundle in which a total of two sheets P1, P2 are stacked.

  Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the two sheets P1 and P2 is the first sheet or the other sheet number. In this example, since the first overlapped sheet is completed, the process proceeds to step ST7 corresponding to the number of overlapped sheets Pi other than the first overlapped sheet Pi. In step ST7, the CPU 55 branches the control depending on whether the succeeding sheet P3 to be superimposed on the two sheets P1 and P2 is the second sheet or the other number.

  In this example, the process proceeds to step ST8, and the switchback conveyance unit 20 takes in the second sheet P3 of overlap, and in step ST9, the CPU 55 changes the conveyance start timing from X seconds to Y seconds, and detects the sheet detection sensor. 12 seconds after turning ON 12, the conveyance of the sheets P <b> 1 and P <b> 2 of the standby position conveyance unit 40 to the switchback conveyance unit 20 is started.

  At this time, in the switchback transport unit 20, when the second overlapped sheet P3 detected by the sheet detection sensor 12 is taken and transported toward a predetermined stacking position, from the time t0 when the sheet detection signal S12 rises. After Y seconds, the motor control signal S44 (2) rising from the low level to the high level shown in FIG.

  The standby position transport unit 40 transports the sheets P <b> 1 and P <b> 2 from the standby position toward the overlapping position based on the rotation of the transport motor 44. As a result, the leading end portions of the sheets P1 and P2 and the leading end portion of the sheet P3 are overlapped at the overlapping position, and a sheet bundle in which a total of three sheets P1, P2, and P3 are overlapped can be sent (see FIG. 5B). Thereafter, in step ST2, the CPU 55 detects the end of the two-sheet stacking mode and ends the sheet stacking control.

[Three stack mode]
If the three-sheet stacking mode is set in step ST1, the CPU 55 takes in the first sheet P1 in step ST3 in the same manner as in the one-sheet stacking mode, and puts the first sheet P1 in the standby position. The transport unit 40 is put on standby. Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the first sheet P1 is the first sheet or the other number.

  In this example, in the same manner as in the single sheet stacking mode, the switchback conveyance unit 20 takes in the first sheet P2 in step ST5, and in step ST6, the CPU 55 X seconds after the sheet detection sensor 12 is turned on. Later, the first sheet P1 of the standby position transport unit 40 is started to be transported to the switchback transport unit 20. As a result, the leading end of the sheet P1 and the leading end of the sheet P2 are overlapped at the overlapping position, and a sheet bundle in which a total of two sheets P1 and P2 are overlapped can be reversed and conveyed to the standby position conveying unit 40. Become.

  In this state, the switchback conveyance unit 20 reversely conveys a total of two sheets P1 and P2 from the overlapping position to the standby position conveyance unit 40. Further, since the CPU 55 detects that the three-ply mode is not completed in step ST2, in step ST3, the standby position transport unit 40 waits for a bundle of sheets in which a total of two sheets P1, P2 are overlapped.

  Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the two sheets P1 and P2 is the first sheet or the other sheet number. In this example, since the first overlapped sheet is completed, the process proceeds to step ST7 corresponding to the number of overlapped sheets Pi other than the first overlapped sheet Pi. In step ST7, the CPU 55 branches the control depending on whether the succeeding sheet P3 to be superimposed on the two sheets P1 and P2 is the second sheet or the other number. In this example, since the second overlapped sheet has been completed, the process proceeds to step ST10, and the CPU 55 branches the control according to whether the subsequent sheet Pi is the third overlapped sheet or the other overlapped sheet number.

  In this example, the process proceeds to step ST11, and the switchback conveyance unit 20 takes in the third sheet P4 of the overlap. In step ST12, the CPU 55 changes the conveyance start timing from Y seconds to Z seconds, and detects the sheet detection sensor. After Z is turned on, Z sheets P1, P2, and P3 of the standby position conveyance unit 40 are started to be conveyed to the switchback conveyance unit 20 after Z seconds.

  At this time, when the switchback transport unit 20 takes in the third overlapped sheet P4 detected by the sheet detection sensor 12 and transports it toward a predetermined stacking position, the rising time t0 of the sheet detection signal S12. Z seconds later, a motor control signal S44 (3) rising from the low level to the high level shown in FIG.

  The standby position transport unit 40 transports the sheets P1, P2, and P3 from the standby position toward the overlapping position based on the rotation of the transport motor 44. As a result, the leading end portions of the sheets P1, P2, and P3 and the leading end portion of the sheet P4 are overlapped at the overlapping position so that a sheet bundle in which a total of four sheets P1, P2, P3, and P4 are overlapped can be sent out. (See FIG. 7A). Thereafter, in step ST2, the CPU 55 detects the end of the three-sheet stacking mode and ends the sheet stacking control.

[4-ply mode]
When the four-sheet stacking mode is set in step ST1, the CPU 55 takes in the first sheet P1 in step ST3 in the same manner as in the one-sheet stacking mode, and puts the first sheet P1 in the standby position. The transport unit 40 is put on standby. Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the first sheet P1 is the first sheet or the other number.

  In this example, in the same manner as in the single sheet stacking mode, the switchback conveyance unit 20 takes in the first sheet P2 in step ST5, and in step ST6, the CPU 55 X seconds after the sheet detection sensor 12 is turned on. Later, the first sheet P1 of the standby position transport unit 40 is started to be transported to the switchback transport unit 20. As a result, the leading end of the sheet P1 and the leading end of the sheet P2 are overlapped at the overlapping position, and a sheet bundle in which a total of two sheets P1 and P2 are overlapped can be reversed and conveyed to the standby position conveying unit 40. Become.

  In this state, the switchback conveyance unit 20 reversely conveys a total of two sheets P1 and P2 from the overlapping position to the standby position conveyance unit 40. Further, since the CPU 55 detects that the four-sheet stacking mode has not been completed in step ST2, in step ST3, the standby position transport unit 40 waits for a sheet bundle in which a total of two sheets P1, P2 are stacked.

  Thereafter, in step ST4, the CPU 55 branches the control depending on whether the succeeding sheet Pi to be superimposed on the two sheets P1 and P2 is the first sheet or the other sheet number. In this example, since the first overlapped sheet has been completed, the process proceeds to step ST7. In step ST7, the CPU 55 branches the control depending on whether the succeeding sheet P3 to be superimposed on the two sheets P1 and P2 is the second sheet or the other number. In this example, since the second overlapped sheet has been completed, the process proceeds to step ST10, and the CPU 55 branches the control according to whether the subsequent sheet Pi is the third overlapped sheet or the other overlapped sheet number. In this example, since the third overlapped sheet has been completed, the process proceeds to step ST13.

  In step ST <b> 13, the CPU 55 takes in the fourth sheet P <b> 5 of which the switchback conveyance unit 20 overlaps, and also changes the conveyance start timing from Z seconds to 0 seconds, turns on the sheet detection sensor 12, and sets the standby position. The conveyance of the sheets P1, P2, P3, and P4 of the conveyance unit 40 to the switchback conveyance unit 20 is started.

  At this time, in the switchback conveyance unit 20, when the fifth sheet P5 detected by the sheet detection sensor 12 is taken and conveyed toward a predetermined overlapping position, simultaneously with the rising time t0 of the sheet detection signal S12. A motor control signal S44 (4) that rises from the low level to the high level shown in FIG. 10F is output to the transport motor 44.

  In the standby position transport unit 40, the sheets P1, P2, P3, and P4 reversely transported to the standby position by the switchback transport unit 20 are one sheet, two sheets, three sheets based on the time t0 when the fifth sheet P5 is taken in. Sheets, fourth sheets P1, P2, P3, and P4 are conveyed from the standby position toward the overlapping position. As a result, the leading ends of the sheets P1, P2, P3, and P4 and the leading end of the sheet P5 are overlapped at the overlapping position, and a total of five sheets of P1, P2, P3, P4, and P5 are stacked. It can be sent out (see FIG. 8B). Thereafter, in step ST2, the CPU 55 detects the end of the four-sheet stacking mode and ends the sheet stacking control.

  As described above, according to the sheet stacking and sending apparatus 100 as the embodiment, the leading ends of the second and subsequent sheets P2, P3, P4, and P5 are superimposed on the leading end of the first sheet P1, and a total of five sheets. When outputting a sheet bundle in which P1 to P5 are overlapped, the control unit 50 sequentially conveys to the standby position conveyance unit 40 according to the standby number of sheets Pi that are waiting, and the conveyance start timing when a plurality of sheets are stacked. The standby position transport unit 40 is controlled so as to sequentially change (X → Y → Z seconds).

  By this control, the alignment accuracy does not decrease due to the difference in the number of sheets Pi to be stacked, and even if the number of stacked sheets changes, the sheets Pi can be stacked with good reproducibility at the same position. A bundle of sheets can be sent out.

  In the above-described embodiment, a case has been described in which the conveyance start timing when stacking a plurality of sheets Pi is sequentially changed in accordance with the number of sheets Pi waiting on the standby position conveyance unit 40, but is not limited thereto. . For example, when the conveyance start timing is sequentially changed, the conveyance speed of the paper Pi conveyed from the standby position conveyance unit 40 to the overlapping position is adjusted based on the conveyance speed of the paper Pi taken into the switchback conveyance unit 20. It may be.

  Here, if the paper Pi capturing speed is v, the speed v is detected by the speed detector. The speed detection unit can also be used as the paper detection sensor 12, and the control unit 50 calculates the speed v based on the paper detection signal obtained from the paper detection sensor 12. The calculation at that time may be obtained as v = L / (t2−t1) from the difference between the leading edge detection time t1 and the trailing edge detection time t2 of the sheet Pi and the length L of the sheet Pi.

  Even in that case, as the number of sheets Pi waiting in the standby position transport unit 40 increases compared to the transport start timing and transport speed when the number of sheets Pi waiting in the standby position transport unit 40 is small, the transport of the paper Pi starts. The standby position conveyance unit 40 is controlled so as to increase the timing, the conveyance speed, and the like. Even with this method of adjusting the conveyance speed, the alignment accuracy does not deteriorate due to the difference in the taking-in speed of the stacked sheets Pi, and even if the number of stacked sheets changes, they can be stacked at the same position.

  The present invention relates to an image forming system constructed by combining a color printer, a monochrome printer, a copying machine, a multi-function printer, a finisher, and the like, with the leading ends of a plurality of recording sheets after image formation overlapped and sent. The present invention is extremely suitable when applied to a sheet stacking and feeding device.

DESCRIPTION OF SYMBOLS 11 Capture roller 12 Paper detection sensor 20 Switchback conveyance part (1st sheet conveyance part)
21 Switchback transport path (first sheet transport section)
22 Forward / reverse roller (first sheet conveying unit)
23 Conveying motor (first sheet conveying unit)
30 branch path 31, 32 transport path 33 branch member 40 standby position transport section (second sheet transport section)
41 Standby transport path (second sheet transport section)
42, 43 Forward / reverse roller (second sheet conveying unit)
44 Conveying motor (second sheet conveying unit)
50 Control unit 51 A / D conversion unit 52 Counter (counting unit)
53 ROM (control unit)
54 RAM (control unit)
55 CPU (control unit)
56 Motor control unit (control unit)
57 System bus (control unit)
100 Sheet stacking device (sheet processing device)

Claims (4)

A sheet processing apparatus that superimposes the leading end portions of the second and subsequent sheet materials on the leading end portion of the first sheet material, and outputs a bundled sheet member,
A sheet detector for detecting the incorporation of the sheet material;
A first sheet conveyance unit that takes in the sheet material detected by the sheet detection unit and conveys the sheet material toward a predetermined overlapping position, and then reversely conveys the sheet material from the overlapping position to a predetermined standby position;
A second sheet conveying unit that conveys the sheet material reversely conveyed to the standby position by the first sheet conveying unit from the standby position toward the overlapping position;
Start of conveyance when there are few sheet materials waiting at the standby position, up to the conveyance time from the detection detection position of the second and subsequent sheets detected by the sheet detection unit until the sheet reaches the overlapping position A control unit that controls the second sheet conveyance unit so as to advance the conveyance start timing of the sheet material as the number of the sheet material waiting at the standby position increases compared to the timing ;
A sheet processing apparatus comprising: A counting unit that counts the number of sheets that are waiting at the standby position;
Wherein the control unit according to claim 1, characterized in that to control the conveyance start timing of the sheet material in which the waiting at the standby position based on the number of the sheet material to wait at the waiting position, which is counted by the counting section the sheet processing apparatus according to. Before Symbol control unit,
Based on the leading edge detection time and trailing edge detection time of the sheet material detected by the sheet detection unit, and the length of the sheet material, the second and subsequent sheet material taking-in speed is calculated, and the calculated the sheet processing apparatus according to claim 1 or 2, characterized in that to adjust the transport speed of the sheet material to be transported to the superposition position from the standby position on the basis of the uptake rate of the sheet material. A sheet processing method for superimposing the leading ends of the second and subsequent sheets on the leading end of the first sheet material and outputting a bundled sheet member,
Detects the sheet material that is sequentially taken into the overlapping position,
The detected sheet material is taken in and transported toward a predetermined overlapping position, and then the sheet material is held in reverse from the overlapping position to a predetermined standby position,
The second and subsequent sheet materials for which uptake has been detected are transported toward the overlapping position, and the first and subsequent sheet materials are transferred based on the detection detection time of the second and subsequent sheet materials. When transporting from the standby position toward the overlapping position and sequentially stacking a plurality of sheet materials that are taken in at the overlapping position,
Compared to the conveyance start timing when there are few sheet materials waiting at the standby position, the standby position is limited to the conveyance time from the detection detection position of the second and subsequent sheets to the overlap position. The sheet processing method is characterized in that, as the number of sheet materials waiting in step increases, the conveyance start timing of the sheet material is advanced .

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